The present invention relates to a disk device including a flaw detecting unit for outputting a flaw detecting signal when a flaw formed in a disk is detected, and more particularly to a disk device in which when it is detected that the flaw detecting signal is outputted at the time of controlling a track jump corresponding to a still reproduction, a timing for starting a subsequent track jump is controlled properly.
In a still reproduction mode of video and audio information recorded in a DVD, a track jump toward an inner peripheral side is carried out by one track for each rotation of the DVD to repeatedly reproduce the same position. Further, in the track jump, after a pulse is applied for accelerating and moving a reading position toward the inner peripheral side, a pulse is applied for reducing the moving speed of the reading position and stopping the reading position. Then, when the track jump is completed, a servo control of a tracking is resumed (This technique is referred to as a first related art).
Further, when a DPD (Differential Phase Detection) signal is used as a tracking error signal, if the landing position of the track jump corresponds to a part (a linking part) in which data is written and connected or a part in which since the data is not recorded, a reproducing RF signal is not obtained, the tracking error signal is undesirably disturbed after the track jump lands so that a reproducing operation cannot be preferably carried out from a desired sector. Thus, a below-described technique is proposed.
Namely, in this technique (This technique is referred to as a second related art), when the track jump is started, it is decided whether or not a landing position obtained when the track jump is carried out from the current reading position is a position suitable for landing. That is, whether the landing position is the linking part or the part in which the data is not recorded is examined. Then, when the landing position is the linking part or the part in which the data is not recorded, a timing of starting the track jump is shifted so that the landing position does not correspond to the linking part or the part in which the data is not recorded. Further, in the technique, the part in which the data is not recorded is a sector that is replaced due to a flaw (for instance, see JP-A-2001-34961).
Further, a below-described technique is proposed (This technique is referred to as a third related art). In this technique, when a track jump is carried out, the applying time of a pulse for carrying out the track jump is determined not on the basis of a tracking error signal, but on the basis of a control signal outputted from a deciding circuit. The deciding circuit decides whether a jump is too sufficient or insufficient from the tracking error signal when the pulse is applied for a prescribed time in the track jump of a previous time to generate the control signal showing a proper applying time in accordance with the decided result. Then, when a subsequent track jump is carried out, the applying time of the pulse for the track jump is determined not on the basis of the tracking error signal, but on the basis of the control signal outputted from the deciding circuit. As a result, even when noise is generated in the tracking error signal owing to the flaw of an optical disk, the track jump is carried out without a difficulty (for instance, see JP-A-5-342783).
However, when the first related art is employed, below-described problems arise. That is, when the flaw is present in the landing position, a normal tracking error signal is not obtained. Therefore, a tracking may not be normally resumed after the track jump. Namely, a situation arises that the track jump of an optical pick-up cannot successfully arrive at an adjacent track so that the reading position of the optical pick-up greatly shifts in the radial direction. Then, when the reading position of the optical pick-up greatly shifts in the radial direction, the level of a tracking error signal may oscillate with a large amplitude so that a driving signal oscillating with a large amplitude is applied to a tracking actuator. As a result, an objective lens greatly oscillates in the radial direction. Thus, an abnormal sound such as creak is generated from a disk drive to give a discomfort to a user.
When the second related art is employed, if a replacement process is carried out so that an area having the flaw is not used, the track jump of the optical pick-up can be avoided from landing at a position where the flaw is present. However, even when there is such a flaw as to disturb the tracking error signal at the time of landing, since all the part having the flaw is not necessarily replaced, a situation may possibly arise that the track jump of the optical pick-up lands at the position having the flaw. Further, in the case of the disk exclusive for a reproduction, since the replacement process is not carried out, the technique cannot be applied. Further, since a process for detecting whether or not the landing position is an area that is subjected to the replacement process includes a complication calculation, the structure of software is undesirably complicated.
Since the third related art is the technique for performing the track jump without referring to the tracking error signal, the third related art is hardly applied to solve the problems in the first related art.